<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>背景</title>
		<style>
			#d1{
				background-color: rgb(10,10,100);
				color: white;
				width: 400px;
			}
			#d2{
				background-color: blue;
				height: 500px;
				background-image:url(../img/full_ask.png);
				background-repeat: no-repeat;
				background-position: 30px 50px;
			}
			#d3{
				background-color: darkgoldenrod;
				height: 500px;
				background-image:url(../img/full_ask.png);
				background-repeat: no-repeat;
				background-position: right bottom;
				opacity:0.2;/*元素透明度*/
				background-size: 400px;
				
			}
		</style>
	</head>
	<body>
		<div id="d1">
			这个div实际占用的空间
		</div>
		<div id="d2">
		</div>
		<div id="d3">
			教育改变生活
		</div>
	</body>
</html>